The night before baking, or at least 8 hours in advance of baking, mix the leaven. Add the starter, 75 grams of all-purpose flour, and 75 grams of warm water into a container and mix until fully combined and no bits of dry flour remain. Cover and allow the leaven to ferment at room temperature for 8 hours or overnight.
The next morning, the leaven should be aerated and doubled in size. Add 300 grams of the warm water to a large mixing bowl, then whisk in 100 grams of the leaven to disperse it. The remaining leaven will become your new starter.
Measure in the all-purpose flour and whole spelt or whole wheat flour. Mix everything well until a sticky dough has formed. I like to start mixing with a dough whisk, then switch to using my hands once the dough comes together. Cover the bowl with a clean dish towel and let it rest at room temperature for 25 minutes.
After the initial resting period, add the salt and the remaining 25 grams of warm water. Squeeze the dough between your fingers to combine. Fold the dough onto itself and cover it with the towel. You are now in the bulk fermentation phase.
To encourage the development of the bread’s gluten, a series of stretch and folds, or “envelope folds,” are completed in 30-minute intervals throughout the 3- or 4-hour bulk fermentation. To complete an envelope fold, reach into the bowl with a clean hand and grab the bottom of the dough, stretch it up, and fold it back over itself. Repeat 3 more times, rotating the bowl 90 degrees between each fold. You have now completed one envelope fold. Cover the dough and allow it to rest for 30 minutes, then repeat another fold. Over the bulk fermentation, you will complete 6 to 8 envelope folds.
Transfer the dough to a clean, floured work surface. Lightly flour the dough, then, using the bench scraper and one hand, shape the dough into a round shape. Cover and let rest on the work surface for 30 minutes—this is known as the bench rest.
Lightly flour the surface of the dough, then use the bench scraper to flip the dough so the floured side is now on the work surface. Grab the edge of the dough closest to you, and stretch it up and over itself. Repeat this movement with the sides of the dough to your left and right. Lastly, stretch the edge of the dough furthest from you up, then fold it over itself, rotating the dough away from you so the seam side is now facing down.
Flour your bread banneton with a 50/50 mix of white flour and rice flour to prevent the dough from sticking. Transfer the shaped loaf to the banneton, flipping it so the seam side is now facing up in the basket.
When it comes to the final rise, you have two options. Option one: You can allow the bread to rise at room temperature for 3 to 4 hours before baking. Option two: you can delay the final rise by transferring the shaped loaf to the fridge to rise slowly overnight, then bake it the following morning. See the suggested baking schedules in the blog post for more details.
If you refrigerated your loaf for the final rise, remove it and allow it to sit on the counter while you preheat the oven. Put the Dutch oven in the centre of the top rack in the oven. Preheat the oven to 500°F with the Dutch oven inside.
Once the oven has come to temperature, flip the loaf out onto a square of parchment. Using a sharp bread lame, hold the blade at a 45-degree angle and carefully score the loaf with your desired pattern.
Using heavyweight oven mitts—let’s not forget this pan is 500 degrees—carefully remove the preheated Dutch oven from the oven. Transfer the scored loaf into the Dutch oven and cover with the lid. Reduce the oven temperature to 450°F and bake the loaf covered for 20 minutes.
After 20 minutes, remove the lid and bake for a further 20 to 25 minutes, until the crust is a deep golden brown and the internal temperature of the loaf reads 205° to 210°F on an instant-read thermometer. Remove the loaf from the oven. Flip the bread out onto a cooling rack. Allow the bread to cool completely before slicing.